#include <stdio.h>
#include <unistd.h>
#include <sys/types.h>

int g_val = 100;

int main() {
    pid_t id = fork();
    if(id == 0) {
        //子进程
        int cnt = 3;
        while(1) {
            printf("我是子进程，g_val = %d, &g_val = %p\n", g_val, &g_val);
            if(cnt-- == 0) {
                g_val = 200;
                printf("我是子进程，我修改了g_val = %d\n", g_val);
            }
            sleep(1);
        }
    }
    else {
        while(1) {
            printf("我是父进程，g_val = %d， &g_val = %p\n", g_val, &g_val);
            sleep(1);
        }
    }
    return 0;
}
